Motor-controlling system.



E. R. GARICHOFF. MOTOR CONTROLLING SYSTEM.

APPLICATION FILED MAY 18, 1905.

Patented Sept. 2, 1913.

WITNESSES:

ATTORNEY COLUMBM IYLANOGRAPH CO.,WASHINGTDN, D. c.

UNITED STATES, PATENT ornron.

EUGENE R. CARICHOFF, OF EAST ORANGE, NEW JERSEY, ASSIGNOR T0 OTISELEVATOR COMPANY, OF JERSEY CITY, NEW JERSEY, A CORPORATION OF J ERSEY.

MOTOR-CONTROLLING SYSTEML.

Specification of Letters Patent.

Patented Sept. 2, 1913.

Application filed May 18, 1905. Serial No. 260,922.

To all whom it may concern Be it known that I, EUGENE R. CARICHOFF,

a citizen of the United States, residing at, East Orange, in the countyof Essex and The main object of my invention is to provide means forautomatically reducing the speed of an electric motor to a predeterminedvalue irrespective of the load and maintaining such reduced speed untilthe motor is stopped.

Another object of my invention is the provision of means forautomatically reducing the speed of an elevator car, as it approaches adesired landing, to a predetermined value irrespective of the load,speed or direction of travel of the car, so that the car shall stop morenearly level with the desired landing floor than is usual in elevatorsnow in operation.

In electric elevator systems in use at the present time, and moreparticularly that designated landing, will frequently overoeed to suchfloor and stop there, the entire run or fall short of the exact floorlevel.

Nearly all of the electric elevators now in use employ a motor whosestunt field alone is excited when the car is traveling cally the samespeed upon ap )roac ing a floor landing with varlous loacs upon the Nowthe brake which is used to stop.

car. such a car is applied by a spring and the braking eflect at eachstop is always the same.

It will readily be seen from the foregoing that where an elevator car isheavily loaded and approaches a landlng where it is desired to stop, ifthe car is descending there will be a tendency to over-run the floorlevel due to the momentum of the load. In a similar manner if the car begoing in an upward direction, the load on the car being heavy, thelatter will fall short of the floor level. lVith such machines, thebrake spring is adjusted to stop the car with an average load at thefloor level, and it becomes apparent that with other than a certainfixed load, a condition which is seldom if ever met with, the elevatorcar will not stop level with a predetermined floor landing. My inventionprovides for just this emergency.

A further object of my invention is the provision of signaling means atthe landlngs.

Other objects of the invention will appear hereinafter, the novelcombinations be ing pointed out in the claims.

Referring now to the accompanying drawing, which illustrates apush-button electric elevator system, E designates the usual car. Anysuitable hoisting mechanism may be used.

In general, the system illustrates one in which a number of push-buttonsare located at each floor landing. The number of buttons P at each floorcorrespond to the number of floors, thus making it possible to call theelevator car from any floor to any one articular fioor, or to send thecar from any oor to any other floor. It is merely necessary to push abutton on any floor corresponding to the floor at which it is desired tohave the car stop. The elevator will then prooperation outside ofpushing a button being automatic. 1

The switch L is an ordinary double pole switch. The floor relays A, B,C, andD are exactly alike in construction, and by referring moreparticularly to relay Dit will be seen that each comprises a solenoid,3, adapted when energized to raise the plunger or core 4 to which arerigidly connected the parts 10 and 15 shown in this instance as rods.The lower end of the rod 10 has a collar 12 firmly attached to it whilethe rod 15 has fastened at its lower end a collar 16. Ufipon these rods10 and 15 are loosely mount- .e the contact-makers 9 and 13,respectively.

11 designates a spring which limits the downward movement of thecontact-maker 9. The lower contact-maker 13 normally rests upon thecontacts 17 and 14. Directly above, and in the path of travel of, thedisk 9 are four fixed contacts 5, 6, 7, and 8 which are engaged andconnected by the contact-maker 9 when the latter is in its raisedposition. This relay is more clearly illustrated in Fig. 3 of my PatentN 0. 677,891, granted July 9, 1901, for an improvement in controllingapparatus for elevators. relays, it will be seen that as soon as thesolenoid 3 is sufficiently energized to raise the plunger 4, thecontact-maker 9 will be carried upwardly by the collar 12 and spring 11until it bridges or makes contact with the four contacts shown directlyabove. The rod 15 is at the same time raised upwardly, sliding freelythrough the contact-maker 13, the latter remaining stationary until thecollar 16 engages it, when it will be raised out of engagement with thecontacts 17 and 14. The spring 11 having been compressed during thisoperation, will firmly hold the upper disk 9 against its contacts. Themain object of this construction is to insure the engagement of theupper disk with its contacts before the lower disk has been raised outof engagement with the contacts 17 and 14.

The motor reversing switches R and R are of similar construction. Adescription of one applies equally as well to the other. The reversingswitch R comprises a solenoid 20 adapted when energized to raise theplunger 21 to which are rigidly fastened the insulated contact-makers orcontact-bridges 22 and 23. Directly above the contact-maker 22 and in aposition to be engaged thereby, are three fixed contacts 24, 25 and 26,and directly above contact-maker 23 and arranged to be engaged thereby,are three fixed contacts 27, 28 and 29. The contactmaker 23 when in itslower position, rests on and bridges the fixed contacts 30 and 31.

r designates a resistance, one end being connected to the contacts 28and 28 and the other end being connected to contacts 31 and 30.

S designates a magnet switch and comprises a plunger carrying a contactplate 18 which is in contact with the fixed contacts 19, 32 and 33except at such times as it is raised by the solenoid 34 into contactwith the fixed contacts 35 and 36, the latter contacts being connectedtogether by the resistance 37.

H designates a magnet-controlled rheostat operated by the solenoid 38through the plunger 39, the latter carrying two contact pieces 45 whichare held in engagement with the contact strip 47 and contacts 48 by thecompression spring 46. A piece of insulation 43 is rigidly mounted uponthe plunger 39 and serves to operate the bell-crank levers Owing to theconstruction of these 40 and 40 which latter serve to establishelectrical connections between the contacts 41 and 42 and 41 and 42,respectively. A contact disk 44 is also fastened to the plunger 39 butinsulated from it and when in its lowermost position bridges the fixedcontacts 50.

I designates a magnet switch whose operating solenoid is connectedacross the armature brushes and which is adapted to control a circuit tothe solenoid 38 of rheostat H through the contacts 54.

M is the hoisting motor, its armature being designated by 55, shuntfield by 56, and

the armature brushes by 57 and 58, respectively. While the motor M isshown as shunt wound, it is to be understood that any type of electricmotor may be used, a shunt motor being shown merely for the purpose ofillustrating one application of my invention and at the same time tomake the various electrical connections as. simple as possible andthereby avoid complexities.

G designates the conventional brake which may be applied to a frictionpulley on the motor shaft by a spring when it is desired to stop thehoisting machine, and released by a magnet when the elevator car is tobe started either up or down.

0, O, O, O' designate the landing door contacts, one for each landing,and are shown connected in series. Thus upon opening any one of thedoors the connection between them is broken.

P, P, P and P designate push-buttons which are what is known asopen-circuit buttons. A set of these buttons is at each floor landingand each set has as many buttons as there are floor landings. In thepresent case this number is four.

F designates a floor controller and in general comprises sets or groupsof contacts each group controlling electrical circuits relative to thedifferent floor landings. These groups may be divided into two halves,one half operating to control the motions of the car in an upwarddirection and the other half operating in a similar manner when the caris descending. The floor controller is preferably connected to the shaftof the ele vator hoist-ing drum by a sprocket chain. The floorcontroller will therefore always be in an exact relative position tothat of the car.

The different sets in each group, indicated by parentheses, are similarin construction, only differing in the manner in which they areconnected electrically. The lowermost set on the Down side, for example,comprises four contacts 68, 69 and 60, 59, which are adapted to bebridged by the contact pieces 70 and 61, respectively. The same appliesto any other set. The Up set of contacts on the Up side are shownconnected, z. 6., bridge piece 64 engages contacts is raised out ofengagement with its contacts.

62 and 63, and bridge piece'67 engages the" their res ective contacts.The bridge 61 closing rst, then brid e 70. Next, the bridges and 81 onto Up side are moved awa from their respective contacts, the piece 8being the first to move. Next, the bridge 83 closes and directlyafterward the bridgle 82. This operation is repeated at the di erentsets of contacts in a similar. manner as the car rises, until finallywhen the car hasreached the top landing, the'{ bridge pieces on the Downside are/all in engagement with their respective contacts, while thebridge pieces on the Up side arei all out of engagement with theirrespective contacts. Should the car go down again,

25 the same operation is gone through witlu only in a reverse manner,and upon the car reaching the bottom landing the same conditions existas before, i. 6., the bridge pieces on the Down side are all out ofengagement with their respective contacts while: the bridge pieces onthe Up side are all in an engaging position with their respectivecontacts.

The operation of such a system as has just been described can be bestshown by pressing one of the buttons, say the top button of the set P.The car being at the bottom landing? and the main line switch L closed,a circuit;

will at once be established from the positive 1 main by wires 2 and 84throu h the landing; door contacts 0, O, O" and (thedoorsi must be intheir closed position); and by y the wire .85 to the contacts 14 and 8of the g floor relay D. Now as the lower contactmakers of the floorrelays are all in their lower positions, the circuit is closed through Ithe lower contacts of these relays to the wire 3 86 which latter iscommon to all of the push buttons P, P, P, P'. The top button of the setP having been pushed, the circuit iscompleted through that button by thewire, 87, the solenoid '3 of relay D, wire .88, hall light 114, and bythe wire 1 to the negative main. The circuit just pointed out includesthe door contacts, the lower contacts of the: floor relays, apushbutton, the solenoid 3 of floor relay D and the hall lamp 114. The

solenoid 3 will now be energized to raise its plunger 4 I together withthe contact-makers 9 and 13. The contact-maker 9 will engage, thecontact 8 before the contact-maker 13' The operation of the relay Dopens the circuit through the wire 86 to the hall but- 85, and contacts8 and 7 to the contact 66 on the floor controller. This contact 66 iscontons, at thecontacts 17 and 14, but not until the circuit to thesolenoid of floor relay D has been completed through the contacts 8 and5. The solenoid of D is now in a selfholding circuit including the doorcontacts 0, O, O" and O' At this juncture it would be manifestlyimpossible to operate the other relays since the common wire 86 of allthe buttons is open circuited at contact 17 Therefore, all thepush-buttons are deenergized. When the upper contactmaker of relay Dbridges the contacts 5, 6, 7 and 8, the positive main is connectedthrough the door contacts by wires 84 and nected by the bridge piece 67and contact 65 to the lowerterminal of the solenoid 34 of the slow downswitch S, the upper terminal of this solenoid being connected by wire 92through the contacts 50 (the contact-maker 44 at this time being in itslowermost position), and wire 89 to the wire 1 and the negative main. Acircuit is thus completed through the solenoid 34 and the contact-maker18 is thereby raised into engagement with the fixed contacts 35 and 36.The operation of the relay D also completed a circuit to the reversingswitch R, this circuit being traced from the positive main by wires84,85, contacts 8 and 6, wire 90, contacts 63 and 62 and bridge-piece 64of the floor controller to the solenoid 20 of switch R. The otherterminal of this solenoid is connected to the negative main by the wire91, contacts 30 and 31, contact-maker 23, contact 30, wire 92, contacts50, and the wires 89 and 1 to the negative main. The solenoid of R isthereby energized to raise its plunger together with its contact-makers'22 and 23. Thecontact-maker 22 bridges the contacts 24, 25 and 26,while the contact-maker 23 bridges the contacts 27, 28" and 29 and atthe same time is raised out of engagement with the contacts 30 and 31.The solenoid of switch R is now open-circuited at 31', thus making itimpossible to energize it so long as the solenoid of switch R is gettingcurrent. In a similar manner it is impossible to get current to thesolenoid of switch R when the solenoid of switch R is energized.

The operation of switch It closes a circuit to the hoisting motor M,this circuit being traced as follows: From the positive main currentflows by wire 2, contacts 36 and 35 (the resistance 37 beingshortcircuited by the contact-maker 18), contacts 26 and 24, andcontact-maker 22, and by wire 93 to the motor armature by the brush 58.Thecircuit continues to the opposite brush 57 which is connected to thecontact strip 47 of the rheostat H, the plunger 3-9 being in itslowermost position. The strip 47 is in electrical connection with theresistance 49 through the lowest of the con' is connected by wire 96,contacts 41 and 42 of switch 40, and by wires 89 and 1 to the negativemain. The field, therefore, receives current at the full line potential,and since the brake G is connected inparallel to the motor field, itfollows that it will be en ergized to release the brake. The motor nowreceives current from the line limited by the resistance 49. The motorfield is fully excited and the brake released. The motor is free tooperate the hoisting ma:

chinery to raise the elevator car.

Upon the operation of the switches R and S, a circuit is closed to thesolenoid 38' of the rheostat H. This circuit may be traced from thepositive main through contact 25, and byvwire 95 to the contacts 54 ofswitch I, solenoid 38, contacts 41 and 42 of switch 40, to the wire 89and negative main 1. The solenoid will therefore be energized to raisethe plunger 39, the sliding wipers 45 operated thereby cutting out theresistance 49 in a well-known way. If desired, a dash-pot of anysuitable construetion may be used to regulate the speed of the plungeras it rises. This cutting out of the resistance 49 allows the motor torun at a higher speed, its armature being connected across the mains. 49has all been cut out a further upward movement of the plunger 39 causesthe insulation piece 43 to strike and operate the small bell-cranklevers40 and 40 which at all other times are closed, thereby breakingthe connection between the contacts 41 and 42, and 41 and 42,respectively. The circuit to the shunt field of the motor is now forcedto traverse the resistance 52, since a circuit from wire 96 by way ofcontacts 41 and 42 to wire 89 and negative main 1 is broken at thecontacts 41, 42, current now flowing from wire 96 to wire 97, resistance52, wire 98, to wires 87 and 89 to the negative main. This will cause areduction in the current strength and consequent weakening of the motorfield which operates to As soon as the resistance,

to prevent any over-heating and waste of energy after the solenoid 38has raised its core or plunger 9, the current required to raise theplunger 39 being greatly in excess of that required to hold the plungerin its uppermost position. i

The operation of the rheostat H opens at the contacts 50, the circuitthrough the solenoids 34 and 20of the switches S and R by way of wire92. The circuit now supplying these solenoids may be traced from thepositive main to the contacts and upper contact-maker of floor relay D,through, the floor-controller F, and through the solenoids 20 and 34.The circuit from the solenoid 20 continues through wire 91, contacts 30and 31 and contact-maker 23, re-

sistanoe 7, contacts 28 and 29 and contactmaker 23, wire 1 to thenegative main, while that from the solenoid 34 continues through aportion of wire 92, to wire 99, contact 30, resistance r, to thenegative main as before. The current passing through the solenoids 20and 34 is therefore reduced by the presence of the resistance r in thecircuit of each. The position that the various parts have I10W assumed,together with the arrangement of the circuits in accordance with theforegoing, correspond to normal full speed, the car traveling upwardly.Shortly before the car reaches the desired landing, in this case the topfloor, the bridge piece 67 on the floor controller is moved out ofcontact with,

the two fixed contacts and 66, interrupting the circuit between them.Now this circuit includes the solenoid 34 of slow-speed switch S. Thesolenoid 34 will be deenergized and allow the contact-maker 18 to dropand electrically connect the contacts 19 and 33. This is productive ofthree results; first, the resistance 37 is inserted in the circuitsupplying the motor with current from the main line; and second, a shuntcircuit is closed around the motorarmature through the resistances 51and 49; and third, the solenoid of switch I is connected across thearmature brushes, one end of the solenoid being permanently connected tobrush 57 and the other end being now connected by contacts 19 and 32 tothe brush 58.

The insertion of the resistance 37 into the armature circuit cuts downthe amount of current flowing from the main line to the motor, causingthe latter to run at a reduced speed. The shunt around the motorarmature through the resistances 51 and 49 further reduces the amount ofcurrent passing through the armature thereby producing a still slowerspeed.

At the time that the solenoid 100 of switch I is connected in circuit,the motor is developing a counter-electromotive force of relatively highvalue. The solenoid 100 will therefore receive sufficient current todoor at the top landin energize the same and raise its contactmaker 101from the contacts 54 which results in opening the circuit to thesolenoid 38 of the rheostat H. The sliding wipers 46 will therefore beallowed to descend to cut out the resistance 49 but the resistance 51remains in circuit. When the core 39 begins to descend, the contacts 41,42 and 41 42 crank levers 40 and 40, respectively, therebyshort-circuiting the resistances 52 and 53.

The cutting out of the resistance 49 from the shunt circuit produces agradual slowing down of the motor until its speed andcounter-electromotive force assumes a value so low that the solenoid 100becomes deenergized to such an-extent that it no longer has suflicientpower to hold its plunger in its upper position. Upon the plunger 102dropping, the contacts 54 are again placed in electrical connection,thereby closing the circuit including the solenoid 38 of rheostat H,which will operate to re-insert the resistance 49 in the shunt circuitacross the armature brushes. As the resistance 49 is being re-inserted,the motor speed and resultant counter-electro-motive force rises again,energizing solenoid 100 of governor switch I causing it to againopen-circuit the solenoid of rheostat H. The latter again cuts out ofcircuit more or less of the re sistance 49.

The switch I by virtue of its connections depends for its operation uponthe counterelectro-motive force of the revolving armature. Thiscounter-electro-motive force is proportional to the speed and load ofthe motor, and since the insertion or cutting out of resistance 49 iscontrolled by the rheostat Hand the latter is dependent for itsoperationupon switch I, it necessarily follows that the motor automatically actsas its own governor, causing its armature to revolve at a constant lowspeed regardless of the load. By the time the car has reached thedesired landing at the top floor, the floor controller operates to openthe circuit to the solenoid 20 of the reversing switch R by removing thebridging piece 64 from the contacts 62 and 63. The core 21 of thereversing switch It now drops, cutting off all current supply to themotor and at the same time applying the brake by open-circuiting itsreleasing coil and allowing the spring to apply the brake shoes. Therelay D remains energized, maintaining its own circuit the same beinclosed throu h the door contacts. In orc er to restore the system to itsnormal condition it is necessary to open one of the doors; in this casethe would be opened, breaking the circuit fee ing relay D, allowing itto drop and thereby restoring the system to a proper condition for anyfurther operation by the push-buttons.

are again connected by the bell If it be desired to bring the car to thebottom landing, it is only necessary to push a corresponding button. Insuch case the relay A is energized to operate in a manner similar tothat of relay D. In this case, however, a circuit to reversing switch Itis closed through the floor-controller contacts 59 and 60 and to theswitch S through the contacts 68 and 69. Circuits to the motorarmature,field and brake are closed as before, except that now the current to thearmature flows in a reverse direction, causing the elevator car todescend. The armature circuit now extends from the positive main bycontacts 36 and 35, 24 and 26, resistance 49, to brush 57 passingthrough the armature to brush 58, the circuit continues by wire 93 andcontacts 29 and 27 to the negative main, the current traversing themotorarmature in a direction reverse to that when the car was ascending.As the car approaches the lower landing, the floor controller operatesto open the circuit of slowspeed magnetic switch S at the contacts 68and 69 and finally by opening the contacts 60 and 59 to stop the car atthe desired floor. The automatic operations of the rheostat H andgovernor switch I takes place as before and causes a reduction inmotorspeed to a low constant regardless of the load so that as the carapproaches the land ing the ultimate efiectis to stop the carsubstantially level with the floor landing. As before, a landing door,as 0 must be opened and shut before another operation is possible.

In order to have either of the reversing switches operate to raise theirplungers and to close a circuit to the motor, it is necessary that allof the resistance 49 is first inserted in the armature circuit. This isaccomplished by the circuit-closer including the small contacts 50. Whenany button is pushed, the corresponding relay operates to close acircuit to the operating solenoid of either of the reversing switches Ror It. This circuit must be completed through the contacts 50, and asthe plunger 39 and disk 44 must be in their lowermost position to dothis, it is apparent that it would be impossible to start the motorunless the resistance 49 was in circuit.

The operation of the system when it is desired to move the car to anintermediate ifloor landing is similar to the foregoing description inconnection with the top or bottom landings, the floor controller inevery case controlling circuits leading to the re versing switches R andR and the slowdown magnet S, while a relay magnet corre sponding to thepredetermined button closes circuits through contacts on the floorcontroller which corresponds to the selected button. M

It will be seen from the drawing that the hall lamps or signal devices111, 112, 113 and 114 are in series respectively with the coils of thefloor relays A, B, C and D and have a common return wire 104 to thenegative main. lVhenever the uppermost pushbutton at any floor landingis operated the signal device 114: at the uppermost landing and onlythat signal device, will be immediately operated no matter where the carmay be at the time. Furthermore, the signal device, shown as a lamp inthis instance, will remain in its indicating position until the car isbrought to the top floor and the door is opened to break the circuit. Soalso if the 15' third floor push-button at any floor be pressed the lamp113 at the third floor will be lighted and remain lighted until the cararrives at that floor, is stopped, and the door is opened. The lamps 111and 112 will be operated in a similar manner by the first and secondfloor push-buttons.

While I have described my invention in connection with an electricelevator system 1 and have shown its operation when applied thereto, andwhile it is particularly adapted to such a system, I do not wish tolimit myself to such a system or to any other particular system in whichan electric motor is used for hoisting or other purposes, my inventionbeing applicable to any and all systems in which it may be desired toproduce an automatic governing or slowing down of an electric motor to aconstant value irrespective of its load.

Having fully described my invent-ion, what I claim and desire to secureby Letters Patent is:

1. In combination with a motor, of a starting resistance in circuittherewith, an electro-responsive device for varying said resistance,means for closing a circuit to said device, a normally short-circuitedresistance in series with the winding of said electroresponsive device,means operated by said device for opening the short-circuit around saidlast named resistance to reduce the current in said winding, anadditional resistance in series with said starting resistance, meanscomprising an electro-magnet for short-circuiting said additionalresistance, a shunt circuit for said electro-magnet, said shunt circuitcontaining resistance to reduce the current through said electro-magnetafter said additional resistance has been short-circuited, and a circuitcloser connected to said electro-responsive device for controlling acircuit to said electro-magnet.

2. The combination with a motor, of resistance, means for varying saidresistance, an electro-responsive device for controlling saidresistance-varying means, means for closing a circuit through saidelectro-responsive device, an additional resistance, means forestablishing a circuit including the motor and said first-namedresistance and for closing a local circuit including said motor and saidresistances in series, and

means for interrupting the first-named circuit through saidelectro-responsive device to control the speed of the motor.

3. The combination with a motor, of motor starting resistance,additional resistance arranged to be placed in series therewith, meansincluding an electro-magnet for conance connected across the motorarmature,

means comprising an electro-magnet for varying sa1d resistance, andmeans for interrupting the circuit through said electro-magnet when themotor exceeds a predetermined speed.

5. The combination with a motor and a main line circuit, of sectionalresistance normally in series with the motor-armature,connecting-mechanism for sa1d resistance, a

solenoid connected across said main line, a core or plunger for thesolenoid and secured to said connecting-mechanism, a second solenoidconnected across the armature, a core for said second solenoid, a switchsecured to said last-named core actuated by said second solenoid tointerrupt the circuit to the first-named solenoid upon themotor-armature attaining excesssive speed.

6. The combination with a motor, of starting resistance therefor, meansfor varying said resistance, additional resistance in a circuitconnected in parallel with said motor when the latter is at rest, anelectro-responsive device for influencing said resistancevarying-means,and means for interrupting said circuit upon starting of the motor andfor closing the same to reduce the speed thereof and also connectingsaid electro-responsive device across the armature to control saidreduction of speed.

7. The combination with a motor, of starting resistance therefor, meansfor varying said resistance, a second resistance arranged to beconnected in series with the motor to reduce the speed thereof, and athird resistance arranged to be connected to said starting resistanceand to still further reduce the speed of the motor.

8. The combination with an electric motor, of sectional resistancenormally in series with said motor, means for varying said resist-ance,an electro-magnet for actuating said varying-means, an additionalresistance and a switch in a circuit in shunt to said motor andsectional resistance, an electro-responsive device, means for operatingsaid switch to interrupt said circuit upon starting the motor and forclosing the same to reduce the speed of the motor before stopping andalso for connecting said electroresponsive device across the armature tocontrol the said resistance-varying means.

9. The combination with a motor, of resistance in circuit therewith,movable contacts for cutting out said resistance to increase the speedof the motor, an electromagnet operating at constant potential forcontrolling said contacts, a switch in circuit with said electro-magnet,a governing magnet for actuating said switch to effect a deenergizationof said electromagnet to allow the latter to reinsert and gradually varysaid resistance or a part thereof to reduce the speed of the motor, andmeans for connecting said governing magnet across the motorarmature tobe controlled by the varying potential thereof.

10. The combination with a motor, of resistance in circuit therewith,movable contacts for varying said resistance, an electromagnet foroperating said contacts, a switch in series therewith, an additionalelectromagnet for cont-rolling said switch, an additional resistance andan additional switch in parallel with said motor and first-namedresistance, and means for opening said additional switch on starting andclosing same on stopping and also connecting said additionalelectro-magnet across the motor-armature so as to be controlled by thepotential thereof.

11. In motor-controlling apparatus, the combination with a resistance,of movable contacts for varying said resistance, an electro-magnetoperating at constant potential for operating said contacts, a switch inseries with said electro-magnet, an additional electro-magnet forcontrolling said switch to eifect a variation in the reduction of speedof the motor in accordance with the load.

12. In motor-controlling apparatus, the combination with resistance in acontrolled circuit, an electro-magnetic device operating at constantpotential for varying said resistance, an additional electro-magneticdevice for controlling said resistance-varying device to efiect the samereduction of speed of the motor with varying loads.

13. The combination with an electric motor, of reversing switches forthe same, a resistance in circuit with the reversing switches, avariable resistance for the motorarmature, an electro-magnetic devicefor controlling the same, an additional electromagnetic device forcontrolling the aforesaid electro-magnetic device; and means forinserting said first-named resistance in series with the motor to reducethe speed thereof, and connecting said additional electro-magneticdevice across the motor-armature to effect the same reduction of speedof the motor before stopping with varying loads.

14. In a push-button electric elevator system, the combination wit-h acar and its motor, of push-buttons corresponding to the variouslandings, reversing switches for the motor, circuits and connections forautomatically controlling said reversing switches, means for varying theresistance of the m0- tor-armature circuit, an electro-magnet forcontrolling said means, an electro-magnetic switch for controlling saidelectro-magnet, and means for automatically controlling saidelectro-magnetic switch to effect a reduction of speed of the motor to apredetermined low value irrespective of the load as the car approaches apredetermined landing, so that the car shall stop substantially levelwith the desired floor.

In testimony whereof, I have signed my name to this specification in thepresence of two subscribing witnesses.

EUGENE R. GARIOI-IOFF.

'Witnessses CHAS. M. NISSEN, W. H. STOKES.

Copies of this patent may be obtained for five cents each, by addressingthe Commissioner of Patents, Washington, D. G.

